Reaction of alkyl cycloparaffins with unsaturated fatty acid



Patented Dec. 12, 1950 REACTION OF ALKYL CY CLOPARAFFINS WITH UNSATURATED FATTY ACID Albert J. Shmidl, Greens Bayou Park, Tex, al-

signor, by meene assignments, to Standard Oil Development Company, Elizabeth, N. 1., a corporation of Delaware No Drawing. Application May 2, 1947,

Serial No. 145,837

scam. (caste-41s) The present invention relates to a process for reacting fatty acids and hydrocarbons. More particularly, the invention is directed to a process for converting alkyl cycloparafiins to naphthenic acids.

Naphthenic acids find wide use in industry as demulsifying agents, as catalysts, as extraction agents, as solvents and as cleaning materials.

They are also used as emulsifying agents and find application in the preparation of fungicides and insecticides. The salts of the naphthenic acids are quite useful in petroleum refining and as wettingagents. Indeed, the uses of naphthenic acids have resulted in a wide demand for these materials and their derivatives. Consequently, processes for producing the naphthenic acids are much in demand especially when a particular acid can be produced in substantially pure form.

Heretofore, the naphthenic acids have been obtained by treatment of selected petroleum fractions with alkaline reagents to form the corresponding salts of the naphthenic acids. The loastal crudes and those from California are especially good sources of naphthenic acids. After the salts of the acids have been formed, the salts are separated from the petroleum fraction and the acids released by acidifying the salt with a mineral acid. There is one great objection to obtaining naphthenic acids by this method and that resides in the difiiculty in segregating a specific acid from the many compounds found in petroleum. Too, the naphthenic acids which are obtained from a selected fraction are mixtures of various acids of diflerent molecular weight and complicate their usage when a purifled acid is desired.

Another commercial source of naphthenic acids is the oxidation of selected petroleum fractions. This source has all the disadvantages of obtaining naphthenic acids from crude petroleum fractions and is further complicated by the fact that the oxygenated products include, besides the naphthenic acids, other oxygenated compounds which in themselves present a problem in separating and recovering the desired acids.

On the other hand, the unsaturated fatty acids are available in purified form and may be obtained commercially with little diinculty. Bimilarly. the naphthenic hydrocarbons, such as methyl cyclopentane and the like, are available in large quantities and substantially purified form.

It is, therefore, the main object of the present invention to provide a process for reacting a naphthenic hydrocarbon with an unsaturated tatty acid to produce a naphthenic acid.

Another object of the present invention is to provide a process for converting alkyl cycloparaiiins to naphthenic acids by alkylating an unsaturated fatty acid with the alkyl cycloparailins.

Still a further object of the present invention is to convert a mixture of an alkyl cycloparaflin and an unsaturated fatty acid to a naphthenic acid having one more carbon atom in a ring than the alkyl cycloparailin by a mechanism involving alkylation and isomerization.

The objects of the present invention are achieved by reacting an alkyl cycloparaiiin with an unsaturated fatty acid under suitable conditions to cause combination of the alkyl cycloparaflin and the unsaturated fatty acid to form a product having acidic properties.

Briefly, the present invention may be described as involving the steps of forming a mixture of an alkyl cycloparaflln such as; methyl cyclopentane and an unsaturated fatty acid such as oleic acid and contacting the mixture with a catalyst such as sulfuric acid which will cause the alkyl cycloparaiiin and the unsaturated fatty acid to undergo an alkylation-isomerization reaction to produce a product having acid reacting properties and having a ring with one more carbon atom than the alkyl cycloparaflln.

The general type of reaction which is effected by the present process is typified by the following equation showing the formation of a naphthenic acid in accordance with the present invention:

The reaction typified by the vabove equation may be conducted at a temperature in the range from about 60 to 300 F. It will'generally be desirable to employ as the catalyst for the alkylation-isomerization reaction those catalysts which have been found useful in these reactions. It may be mentioned that concentrated sulfuric acid, the aryl sulfonic acids, phosphoric acid, the Friedel-Crafts type catalyst such as aluminum chloride and the like may be employed.

The ease with which the above reaction occurs is probably due to the presence of a tertiary carbon atom in the allqrl cycloparaiiln molecule. It is diillcult to follow the character of such reactions and the formation of amounts of intermediate addition compounds with the organic radical in the catalyst makes the above explanation somewhat inadequate. The reaction exemplined by the equation also omits mention of the formation of more highly alkylated materials and also the formation of any polymers of the unsaturated fatty acid. When conditions are controlled, however, the polymerization reaction is substantially suppressed and the alkylationilomeriaation reaction is favored to obtain maximum yields oi the desired compound.

When practicing the present invention, it will be desirable to add the catalyst and the unsaturated fatty acid to the alkyl cycloparaflin. For example, the alkyl cycloparaflln may e placed in a suitable reactor vessel and vigorously agitated. The catalyst, for example sulfuric acid. and the unsaturated fatty acid is then added to the albl cycloparailin over a period of time ranging up to about three hours while maintaining a temperature in the range given before. Ordinarily, temperatures from about 70 to 90 1''. will be suitable for the reaction. Also higher temperatures may be employed if desired.

The unsaturated fattyacids which may be employed as one feed stock in the present invention may include geranic, linoleic, citronellic, angelic, erucic, brassidic, and the other members of the same homologous series including oleic acid and other similar fatty acids.

The allavl cycloparailin may be exemplified by methylcyclopentane; however, other alkyl cycloparailins may be employed. For example, it may be desirable to employ dimethyl cyclopentane and other higher members of the same homologous series.

The amount of reactants to be used will generally be in equal molar ratio. However, ratios of alkyl cycloparailln to unsaturated fatt acid may range from about 1:1 to about 4:1. It will usually be desirable to maintain the alkyl cycloparaflin in equal amounts or in excess of the unsaturated fatty acid.

The sulfuric acid used as the catahrst for the reaction is preferably of a concentration between 85 and 100%. However, the sulfuric acid catalyst may contain as much as 5 to sulfuric anhydride in 100% sulfuric acid. The sulfuric acid may be used alone or in combination with other materials designed to favor the alkylationisomerization reaction.

The nature of the reactants are such that the reaction may be carried out under substantially atmospheric conditions. The alkyl cycloparaflln has a vapor pressure sufliciently low that it is a liquid at ordinary atmospheric conditions. Similarly, the vapor pressures of the higher members of the homologous: series of unsaturated fatty acids have low Vapo'. pressures and atmospheric conditions may be employed. However,

when the lower members of the unsaturated fatty acid are employed as a feed stock, it may be desirable to superimpose pressures such as ,15 to 100 pounds on the reaction vessel.

While the temperatures have been illustrated to be in the range of 60 to 300 F., it will or- 4 dinarily be preferable to employ temperatures from about 70 to about 120 F.

The following example is given as illustrative of the results obtainable in the practice of the present invention. However, the data are given by way of illustration and are not to be construed as imposing any limitation on the scope of the invention. Methyl cyclopentane was reacted with oleic acid in the presence of 95% sulfuric acid at a temperature maintained between 70 and 80 F.; 0.5 mole of methyl cyclopentane was placed in a suitable reactor provided with an agitator. The agitating means was operated to stir the methyl cyclopentane violently. To the agitated methyl cyclopentane was added 0.38 mole of oleic acid and 0.45 mole of sulfuric acid of the. strength mentioned before. The stirring was continued throughout the period during which the sulfuric acid and the oleic acid were added. This addition occurred over a threehour period. The temperature was maintained in the range mentioned before until :he reaction was substantially complete. At the end or? the three-hour reaction period, the agitato. as discontinued and a product was 1"..COV91Gd from the reaction vessel having a dark viscous appearance. The amount of methyl cyclopentane added had completely disappeared. The product was dissolved in diethyl ether and analyzed and it was found that an acid representing approximately 60% of the theoretical yield had been formed. The remaining material was substantially unreacted oleic acid.

When practicing the present invention, it is desirable to use an unsaturated fatt acid having at least 4 carbon atoms; otherwise, the reaction illustrated by the equation given above will not proceed since it will be seen that it is necessary for the cycloparaflln ring to open and have the straight chain of the unsaturated fatty acid become a part of the ring. It is understood, of course, that I do not intend to bind myself by any explanation of the mechanism of the reaction which allows obtaining the beneficial results of the present invention.

The nature and objects of the present invention having been fully described and illustrated,

what I wish to claim as new and useful and to secure by Letters Patent is:

1. A method for reacting methyl cyclopentane with oleic acid which includes the steps of forming a mixture of methyl cyclopentane and oleic acid in an acid reacting alkylaation-isomerization catalyst, contacting the mixture with the acid reactin alkylation-isomerization catalyst at a temperature in the range between 60 to 300 F. for a time sufficient to form a. reaction product, and recovering the product.

2. A method for reacting: an alkyl clopen tane to form an acid reacting product having one more carbon atom in the ring than the alkyl cyclopentane which includes the steps of forming a pool of an alkyl cyclopentane, heating the pool to a temperature in the range between 60 and 300 F. while vigorously agitating it, adding to the agitated heated pool an acid reacting alkylation-isomerization catalyst and an unsaturated fatty acid for a time sufficient to form a product having one more carbon atom in the ring than the alkyl cyclopentane, discontinuing the agitation, and recovering the product from the pool.

3. A method for reacting methyl cyclopentane and oleic acid which includes the .-.teps of forming a poolof methyl cyclopentane, heating 5 the pool to a, temperature in the range between REFERENCES CITED 70 and 80 F. while vigorously agitating it, adding a mixture of sulfuric acid and oleic acid to 3 g fi g f are or record in the heated agitated pool, continuing the agitation of the heated pool for a time suflicient to 5 UNITED STATES PATENTS form a product having acid reacting qualities Number Name t while maintaining the temperature in the range 2,082,459 mean June 1, 1937 between 70 and 80 F., discontinuing the az ta- 2,230,005 Maser Jan. 28, 1941 tionand recovering said product from the pool. 3,370,494 schmerling Feb. 27, 1945 i0 2379.550 Sutton et a1. July 3, 1945 A ERT S 2,385,300 Pines et a1. Sept. 18. 1945 

1. A METHOD FOR REACTING METHYL CYCLOPENTANE WITH OLEIC ACID WHICH INCLUDES THE STEPS OF FORMING A MIXTURE OF METHYL CYCLOPENTANE AND OLEIC ACID IN AN ACID REACTING ALKYLATION-ISOMERIZATION CATALYST, CONTACTING THE MIXTURE WITH THE ACID REACTING ALKYLATION-ISOMERIZATION CATALYST AT A TEMPERATURE IN THE RANGE BETWEEN 60 DEGREE TO 300 DEGREE F. FOR A TIME SUFFICIENT TO FORM A REACTION PRODUCT; AND RECOVERING THE PRODUCT. 